The present invention relates to servomotors in general, and more particularly to improvements in fluid-operated servomotors which can be utilized to actuate various types of machines, apparatus or other aggregates, such as clutches in automotive vehicles. Still more particularly, the invention relates to improvements in fluid-operated servomotors of the type disclosed in the aforementioned copending patent application Ser. No. 261,292 wherein a piston is reciprocable in a housing in response to evacuation of air from or admission of air into, a chamber at one side of the piston, and the piston is connected with a motion transmitting member which can actuate the aggregate or aggregates.
The servomotor which is disclosed in the copending application Ser. No. 261,292 is constructed and assembled in such a way that the opening of a first valve results in connection of the chamber with a suction generating device or a source of compressed air, and opening of a second valve results in connection of the chamber with the atmosphere. The motion transmitting member is coupled to the piston by a compensating device which allows for axial shifting of the motion transmitting member in one end position of the piston so that the motion transmitting member can select its axial position in dependency on the extent of wear upon the parts of the aggregate and/or other parameters. The piston bears against a first section of the housing of the servomotor in the one end position and against another section of the housing in another end position. A membrane which forms part of, or is connected to, the piston serves as a means for preventing uncontrolled communication of the chamber with the atmosphere, e.g., along the aforementioned motion transmitting member. The membrane is subjected to extensive stresses, particularly while the chamber is connected with the suction generating device.